In a working vehicle having outriggers for stabilizing a vehicle body of a working vehicle such as a crane, it is necessary to maintain to level the vehicle body even on an inclined ground.
Accordingly, there is proposed a device for automatically levelling the vehicle body even on the inclined ground as disclosed in Japanese Patent Publication No. 2-30906.
However, when the vehicle body is levelled by the aforementioned conventional vehicle body levelling device for a working vehicle, it is necessary firstly to extend each hydraulic jack unit to its maximum, then, to contract each hydraulic jack unit so as to level the vehicle body in response to a signal issued by an inclination detector means, which causes such inconvenience that a working efficiency is lowered since it takes time from the start of operation to the completion of levelling of the vehicle body.
Further, since the conventional device starts the levelling control from the state where the hydraulic jack unit is in its maximum stroke to thereby lift the vehicle body to the maximum height, in ordinary case, the levelling control is frequently completed at the state where the vehicle body is lifted to its maximum.
As a result, the position of the center of gravity of the vehicle body becomes high, which makes the device unstable during the operation thereof.
The invention is made to improve such a drawback and to provide a vehicle body levelling device for a working vehicle having outriggers which is capable of levelling the vehicle body in a short period of time, and particularly to provide a vehicle body levelling device for a working vehicle having outriggers which is capable of levelling the vehicle body in a position where the center of gravity of the vehicle body is low.